Interest of ImmunoCAP System to Recombinant ω-5 Gliadin for the Diagnosis of Exercise-Induced Wheat Allergy

Abstract

Background: ω-5 gliadin is a major allergen in exercise-induced wheat allergy (EIWA), but it is also implicated in immediate-type reactions to wheat. An ImmunoCAP assay to measure ω-5 gliadin-specific IgE has become available. This study aimed to evaluate this new biological test in wheat allergy diagnosis and to also determine if it was able to discriminate EIWA from other types of wheat allergy. Methods: Sixty-one patients with wheat allergy were divided into 3 groups as a function of their symptoms (EIWA, immediate-type reactions and atopic dermatitis). These patients underwent skin prick tests with purified ω gliadins and ImmunoCAP to wheat flour, gluten and recombinant ω-5 gliadin. Results: The experimental data showed that 78% of EIWA patients had a positive skin prick test to natural ω-5 gliadin and the same proportion had detectable specific IgE to recombinant ω-5 gliadin, indicating that ω-5 gliadin is the main allergen, but not the only one, in our population. Additionally, we showed that this detection was not EIWA specific since ω-5 gliadin-specific IgE was detected in 30% of other patients who had a wheat allergy. These results lead to a positive predictive value of 37.5% and to a negative predictive value of 91%. Conclusions: Although not specific to EIWA, the new ImmunoCAP ω-5 gliadin is an important biological test because of its negative predictive value. In case of food-dependent exercise-induced allergy, the absence of ω-5 gliadin-specific IgE will almost completely exclude the implication of wheat.

Antibody reactivity in patients with IgE-mediated wheat allergy to various subunits and fractions of gluten and non-gluten proteins from ω-gliadin-free wheat genotypes

“…It seems obvious as the ω-5 gliadin fractions act as the main allergens in WDEIA [18,[32][33][34]. However, ω-5 can be also active in other wheat allergies [21,35].…”

“…One of the important findings in allergology was to prove that ω-5 gliadins are the main allergens involved in wheat-dependent exerciseinduced anaphylaxis (WDEIA) -the most dangerous, life threating form of wheat allergy [16][17][18]. Omega-5 gliadins may also trigger other wheat allergies, described as exerciseinduced wheat allergy (EIWA) [18].…”

“…In turn, ω-1.2 gliadins were evidenced to be allergenic for patients with atopic dermatitis [19]. LMW glutenins play an important role in the development of immediate hypersensitivity to hydrolyzed wheat proteins (IHHWPs) baker's asthma, atopic dermatitis and EIWA [18,20]. Battais et al showed elevated levels of IgE antibodies against all GP in the sera of 28 patients with atopic dermatitis, asthma, urticaria and eczema, which suggested that these proteins were important factors contributing to disease development [21,22].…”

Development and characteristics of ω-gliadin-free wheat genotypes

“…Other gliadin classes, however, especially cgliadins, may also be active in anaphylactic reactions (Palosuo et al 1999;Morita et al 2000) but to a lesser extent. Jacquenet et al (2009) concluded that elimination of x-5 gliadins may completely eliminate the risk associated with consumption of foodstuffs made from wheat flour.…”

Diagnostic Value of the Serum-Specific IgE Ratio of ω-5 Gliadin to Wheat in Adult Patients with Wheat-Induced Anaphylaxis

“…In clinical practice, immunoglobulin E (IgE) specific to wheat or ω-5 gliadin can be measured using the ImmunoCAP system (Phadia, Uppsala, Sweden) [4]. …”